Mathlib v3 is deprecated. Go to Mathlib v4

Theorem set.subsingleton.eq_empty_or_singleton

Modification history

2020-02-02 10:49
src/data/set/basic.lean
feat(data/set/basic): define `set.subsingleton` (#1939) …
Added set.subsingleton.eq_empty_or_singletonView on Github →